JPS62168945A - Fuel control device for engine - Google Patents

Abstract

PURPOSE:To enable a fuel supply amount to obtain a value in accordance with a dry condition in the internal wall surface of an intake passage, by supplying fuel for a predetermined time adding fuel of amount in accordance with an operative condition, when fuel supply is stopped, to the fuel of regular amount, when the fuel, after its supply is stopped, is resupplied. CONSTITUTION:In a control unit 100, when a detection output, which shows an engine operative condition to satisfy a predetermined condition for fuel supply to be stopped, comes to be not obtained, an air-fuel ratio control valve 21 is opened, and the fuel supply is restarted. Here fuel is supplied for a predetermined time from the point of fuel supply restart time adding fuel of amount in accordance with an operative condition in a fuel supply stop condition to the fuel of regular amount. A fuel increase value in this time is obtained from an increase correction coefficient, set in accordance with a fuel supply stop time, intake negative pressure from a negative pressure sensor 22, engine speed from a speed sensor 32, cooling water temperature from a water temperature sensor 41 and an intake temperature from an intake temperature sensor 45, and the fuel increased value obtains a value in accordance with a dry condition in the internal wall surface of an intake passage 12.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention supplies fuel to an engine according to its operating state, and when the operating state of the engine satisfies predetermined conditions, the engine is supplied with fuel according to its operating state. The present invention relates to a fuel control device for an engine that is configured to stop fuel supply.

(Prior Art) Conventionally, as a technology related to engines installed in automobiles, etc., when the operating state of the engine satisfies a predetermined condition, for example, the engine rotation speed is above a predetermined value, and
The throttle valve linked to the accelerator pedal is almost fully closed (
When the engine is in the idling opening state, the so-called deceleration fuel cut is performed, which stops the fuel supply to the engine.
After that, when the operating condition of the engine no longer satisfies predetermined conditions, the fuel supply to the engine is restarted, so-called fuel recovery, which improves fuel efficiency and reduces harmful components contained in exhaust gas. It is known to do.

In an engine in which the deceleration fuel cut and subsequent fuel restoration 1) are performed under predetermined conditions in this way, the fuel adhering to the inner wall surface of the intake passage may be atomized during the deceleration fuel cut. However, if the deceleration fuel cut state continues for a relatively long time, the intake passage will
The inner wall surface is in a so-called dry state with almost no fuel adhering to it.

If fuel is restored with the intake passage dry, the fuel will adhere to the inner wall of the intake passage before being supplied to the combustion chamber. A fuel supply delay (fuel return delay) occurs depending on the dry condition. For this reason, the necessary amount of fuel is not supplied to the combustion chamber immediately after the fuel is restored, causing torque shock in the engine, or undesirable effects, especially if the engine speed is relatively low when the fuel is restored. There is a possibility that the engine may stop.

Therefore, in order to eliminate such inconveniences, for example, as shown in Japanese Patent Application Laid-open No. 1721/1982, immediately after the fuel is restored, the normal amount of fuel set according to the operating state of the engine is maintained for a predetermined period of time. An engine fuel control device has been proposed which supplies an increased amount of fuel to the engine.

(Problems to be Solved by the Invention) However, in the conventionally proposed engine fuel control device as described above, the fuel increase value at the time of fuel restoration is different from the engine operating state at the time of deceleration fuel cut. Since it is set uniformly regardless of the relationship, the necessary amount of fuel may not be supplied to the combustion chamber immediately after the fuel is restored, which may cause problems such as torque shock in the engine. In order to reduce this inconvenience, if the fuel increase value immediately after fuel return is set to a large value, if fuel return is performed with a relatively large amount of fuel adhering to the inner wall surface of the intake passage, the combustion chamber If a too rich air-fuel mixture is supplied to the engine, the air-fuel ratio will shift to the rich side, which may not only worsen fuel efficiency but also cause problems such as an increase in harmful components in the exhaust gas and a deterioration in driving performance. be.

In view of the above, the present invention takes a state in which fuel supply to the engine is stopped when the operating state of the engine satisfies predetermined conditions, and when restarting fuel supply to the engine, a normal amount of fuel is supplied for a predetermined period of time. Moreover, by adjusting the increase amount of fuel immediately after resuming fuel supply according to the dry condition of the inner wall surface of the intake passage, the torque at the time of fuel return can be increased without deteriorating fuel efficiency. An object of the present invention is to provide a fuel control device for an engine that can suppress the occurrence of shocks and the like.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the engine fuel control device according to the present invention, as shown in the basic configuration in FIG. a detection means, a fuel supply means for supplying a regular amount of fuel to the engine according to its operating state, based on a detection output obtained from the operating state detection means; and a fuel supply amount control means for controlling the fuel supply amount, and the fuel supply amount control means causes the fuel supply means to stop the fuel supply when the operating state of the engine represented by the detection output obtained from the operating state detection means satisfies a predetermined condition. At the same time, after the fuel supply has been stopped, a regular amount of fuel is supplied according to the engine's operating state in the fuel supply stopped state for a predetermined period of time from the time when the engine's operating state no longer satisfies the predetermined conditions. It is assumed that the system will be able to supply fuel in addition to the amount of fuel.

(Function) In the engine fuel control device according to the present invention configured as described above, when the operating state of the engine satisfies a predetermined condition, the operating state detecting means detects this and supplies the detected output to the fuel. supply to the quantity control means. As a result, the fuel supply amount control means stops the fuel supply means from supplying the normal amount of fuel. The fuel supply amount control means causes the fuel supply means to resume supplying fuel when the operating state detection means no longer provides a detection output indicating that the operating state of the engine satisfies a predetermined condition.

At this time, the fuel supply amount control means informs the fuel supply means of the operating state of the engine in the state where the fuel supply is stopped for a predetermined period from the time when the fuel supply is resumed, such as the engine rotation speed, the intake temperature, and the like.
A state is established in which an amount of fuel corresponding to the intake negative pressure, engine cooling water temperature, etc. is added to the regular amount of fuel.

This allows for a predetermined period of time from when fuel supply is resumed.
The amount of fuel supplied is increased by an amount corresponding to the dry state of the inner wall surface of the intake passage, and as a result, the occurrence of torque shock and the like is alleviated without deteriorating fuel efficiency when the fuel is restored.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an example of an engine fuel control device according to the present invention, together with an engine to which it is applied.

In FIG. 2, the engine body 10 includes an intake passage 12.
and an exhaust passage 26 are connected to the air cleaner 11.
The intake air taken in through the engine body 1 is passed through the throttle valve 16 of the carburetor 15 provided in the intake passage 12.
0 combustion chamber. The carburetor 15 is of a well-known type and includes an air-fuel ratio control valve 21 and a slow-cut solenoid valve 24 driven by an actuator such as a stamping motor or a solenoid.

The air-fuel ratio control valve 21 is capable of stopping or regulating fuel supply to the main system depending on the operating state of the engine, and when the air-fuel ratio control valve 21 is in the closed state, the fuel supply to the engine is stopped. When the fuel supply is stopped and the air-fuel ratio control valve 21 is driven to open, fuel is supplied to the engine via the main nozzle, and the opening amount (effective opening area, An amount of fuel is supplied to the engine according to the valve opening time per unit time, etc.). Furthermore, when the slow cut solenoid valve 24 is turned on, fuel supplied to the engine through it is cut off.

In this example, the control unit 100 controls the air-fuel ratio control valve 21 and the slow-cut solenoid valve 24 to control the amount of fuel supplied to the engine.
is provided. The control unit 100 receives a detection signal sb corresponding to the intake negative pressure from a negative pressure sensor 22 provided downstream of the throttle valve 16 in the intake passage 12, and a detection signal sb corresponding to the intake negative pressure when the throttle valve 16 is in a substantially fully closed state. A detection signal Si obtained from the idle switch 34 which is in the on state, a detection signal Sn corresponding to the engine rotation speed obtained from the rotation speed sensor 32 arranged in relation to the crank mechanism of the engine main body IO, and a detection signal Sn obtained from the shift lever 35. a detection signal Sd obtained from a neutral switch 36 that is arranged in relation to the engine body 10 and is in an on state when a transmission (not shown) connected to the engine body 10 via a clutch is not in a neutral state; A detection signal SC obtained from a clutch switch 38 that is arranged in relation to the clutch pedal 37 and takes an on state when the clutch pedal 37 is not depressed, and a detection signal SC obtained from the engine main body 10
A detection signal Sw corresponding to the engine cooling water temperature obtained from the water temperature sensor 41 provided in the exhaust passage 26, a detection signal So obtained from the 02 sensor 43 provided in the exhaust passage 26 to detect the oxygen concentration of exhaust gas, and A detection signal Sk corresponding to the intake air temperature obtained from an intake air temperature sensor 45 provided at 12 is supplied.

The control unit 100 receives the above-mentioned detection signal Sb,
Si, Sn, Sd, Sc, Sw and S.

Based on this, a fuel supply control signal Cf and a slow cut control signal Cs are formed and supplied to the air-fuel ratio control valve 21 and the slow cut solenoid valve 24 to control the fuel supply to the engine. In this case, when the engine is in a normal operating state, the control unit 100 sets the air-fuel ratio of the air-fuel mixture supplied to the engine to a predetermined value based on the detection signals So, Sb, Sw, and Sn. A fuel supply control signal Cf having a duty of is generated and supplied to the air-fuel ratio control valve 21, and the supply of the slow-cut control signal Cs to the slow-cut solenoid valve 24 is stopped. As a result, when the engine is in a normal operating state, a normal amount of fuel corresponding to the current operating state is supplied to the engine, and the air-fuel ratio is maintained at a predetermined value.

On the other hand, when the operating state of the engine satisfies a predetermined condition, for example, the engine speed is above a predetermined value, the throttle valve 16 is set to a substantially fully closed state, and the transmission is The clutch pedal 37 is not in the neutral position, and the clutch pedal 37 is not in the neutral position.
is in the open state and the clutch is in the connected state, the supply of the fuel supply control signal Cf to the air-fuel ratio control valve 21 is stopped, and the slow-cut solenoid valve 2
4 to supply a slow cut control signal Cs to perform a deceleration fuel cut to stop the fuel supply to the engine,
When the operating state of the engine no longer satisfies predetermined conditions, the supply of the slow-cut control signal Cs to the slow-cut solenoid valve 24 is stopped, and the air-fuel ratio control valve 2
The supply of the fuel supply control signal Cf to the fuel supply control signal Cf is restarted to perform fuel recovery. At this time, the control unit 100 sets the duty of the fuel supply control signal Cf supplied to the air-fuel ratio control valve 21 for a predetermined period of time from the start of fuel return to the intake air temperature and intake negative pressure at the start of deceleration fuel cut.

Based on the engine cooling water temperature, engine rotational speed, etc., and the deceleration fuel cut time measured by a built-in timer, it is set to be larger than that corresponding to the operating state of the engine at the time of fuel restoration. As a result, the actual amount of fuel supplied to the engine is increased from the normal amount by an amount corresponding to the dry state of the intake passage 12 for a predetermined period of time from the start of fuel return.
As a result, the occurrence of torque shock and the like upon fuel recovery is suppressed without deteriorating fuel efficiency.

For example, the control unit 100 is configured using a microcomputer, and an example of a program executed by the microcomputer in such a case is described as a third example.
This will be explained with reference to the flowchart shown in the figure.

This program starts when the engine is started. After starting, first, initial settings are performed in process 101, the deceleration flag F is set to O, and the process proceeds to process 102. In the process 102, various detection signals Sb, Si, S
Input n, Sd, Sc, Sw, So and Sk. And the following decisions 103, 104, 105 and 10
6, the detection signals Si, S input in the process 102
n.

Based on Sd and Sc, the idle switch 34
is in the ON state, whether the engine speed N is equal to or higher than a predetermined value No, and whether the neutral switch 36 and the clutch switch 38 are in the ON state. , the throttle valve 16 is in a substantially fully closed state, the engine speed N is above a predetermined value N0, the transmission is not in the neutral position, and the clutch pedal 3 is in a substantially closed state.
If it is determined that 7 is in the open state and the clutch is in the connected state, the process proceeds to process I07, where the deceleration flag F is set to 1 indicating the deceleration fuel cut state, and then the process proceeds to process 108. In process 108, a slow cut control signal Cs is supplied to the slow cut solenoid valve 24 in order to cut the deceleration fuel, and the air fuel ratio control valve 2
The supply of the fuel supply control signal Cf to I is stopped. This stops the supply of fuel to the engine.

Subsequently, in decision 109, it is determined whether or not the deceleration flag F has changed from 0 to 1. If it is determined that the deceleration flag F has changed from O to 1, the process proceeds to process 110, where a built-in timer I is started and deceleration is started. Fuel cut time TC
After starting the measurement, the process proceeds to process 111. In process 111, the detection signals Sb, Sn, Sw, and Sk inputted in process 102 are used to incorporate intake negative pressure B, engine rotation speed N, engine cooling water temperature W, and intake air temperature K at the start of deceleration fuel cut. After storing the information in memory, the process returns to process 102. Furthermore, if it is not determined in decision 109 that the deceleration flag F has changed from O to 1, processes 110 and 111
The process returns to process 102 without going through.

-4. When it is determined in decision 103 that the idle switch 34 is not in the on state.

If it is determined in decision 104 that the engine rotation ON is less than the predetermined value 80, then decision 105
If it is determined that the neutral switch 36 and the clutch switch 38 are not in the on state in steps 1 and 106, respectively, processes 1 and 2 are performed to control the fuel supply.
After setting the deceleration flag F to 0, the process advances to process 113. In process 113, the detection signals Sb, Sn, Sw, and So input in process 102 are detected, and regular fuel supply is performed based on the intake negative pressure B, engine rotation speed N, engine cooling water temperature W, and oxygen concentration of exhaust gas. Set the scale. In the following decision 114, the deceleration flag F is set to 1.
It is determined whether or not the value has changed from 1 to O. If it is determined that the value has changed from 1 to O, the process proceeds to process 115.

In process 115, the fuel increase value ΔD at the time of fuel return
Set. This ΔD is, for example, an increase correction coefficient Et that is set according to the deceleration fuel cut time Tc measured by the timer ① started in process 110,
Intake negative pressure B, engine speed N, engine cooling water temperature W
and the increase correction coefficient set according to the intake air temperature K.
, En.

If Ew and Ek are 1, ΔD=P-Et-Eb-En
It is calculated based on the relationship -Ew-Ek (where P is a constant). In this case, each increase correction coefficient Et, Eb, En,
Ew and Ek are, for example, as shown in Figure 4 A, B, C, D and E.
As shown in <, deceleration fuel cut time Tc, intake negative pressure B
, engine rotation speed N, engine cooling water temperature W and intake air temperature K are at predetermined values T+, B+, N+, W+,
Below the values, the larger they become, and therefore, the easier it is for the fuel adhering to the inner wall surface of the intake passage 12 to evaporate, the larger the value becomes.
W+ and 1 or more are assumed to take a constant value, and are stored in advance as fuel increase correction maps in the built-in memory, and the deceleration fuel cut time T is determined from these fuel increase correction maps.
c and intake negative pressure B at the time of starting the deceleration fuel cut stored in process 111;

It is set by reading values corresponding to the engine rotation speed N, the engine cooling water temperature W, and the intake air temperature K.

In the next process 116, a fuel increase time Tf at the time of fuel return is set. This fuel increase time Tf is, for example, similar to the fuel increase value ΔD set in process 115, as well as the fuel increase time coefficient set according to the deceleration fuel cut time Tc measured by timer I started in process 110. If Gt is the intake negative pressure B, engine speed N, engine cooling water temperature W, and intake air temperature K, the increase time coefficients are Gb, Gn, Gw, and Gk, then Tf=Q-Gt-Gb. -Gn-Gw-Gk (however,
Q is a constant). In this case, the increase time coefficients Qt, Gb, Gn.

The increase correction coefficients Et and Eb mentioned above are also used for Qw and Gk.
, En, Ew and Ek, the deceleration fuel cut time T
c, intake negative pressure B, engine rotational speed N, engine cooling water temperature W and intake air temperature K below the respective predetermined values. It takes a value that increases as the fuel increases, and takes a constant value above a predetermined value, and is stored in advance as fuel increase time maps in the built-in memory, and from these fuel increase time maps, the deceleration fuel cut time Tc and the process 111 are calculated. Intake negative pressure B at the deceleration fuel cut start time stored in
, engine rotational speed N, engine cooling water temperature W, and intake air temperature K are read out.

In this way, in process 115, the fuel increase value ΔD is
After each fuel increase time Tf is set in process 116, the process proceeds to process 117, where the timer I started in process 110 is reset, and the process proceeds to process 118. In process 118, the built-in timer
After loading and starting the fuel increase time Tf set in step 16 and starting measurement of the fuel increase time Tf, the process advances to decision 119.

On the other hand, if it is determined in decision 114 that the deceleration flag F has not changed from 1 to O, the process proceeds to decision 119 without going through processes 115 to 118. It is determined whether or not the fuel increase time Tf has elapsed. If it is determined that the fuel increase time Tf has not elapsed, the process proceeds to process 120.

In process 120, the fuel increase value ΔD set in process 115 is added to the regular fuel supply amount set in process 113 to set a new fuel supply amount, and the process proceeds to process 121. Then, in process 121,
At the same time as stopping the supply of the slow cut control signal Cs to the slow cut solenoid valve 24, a fuel supply control signal cr having a duty corresponding to the new fuel supply amount set in process 120 is formed and used to control the air-fuel ratio. Supply valve 21 and then return to process 102.

As a result, for a predetermined period of time (fuel increase time Tf) from the start of fuel return, fuel is supplied to the engine in an amount equal to the regular fuel supply ID plus the fuel increase value ΔD according to the operating state of the engine.

Further, if it is determined in decision 119 that the fuel increase time Tf has elapsed, the process proceeds to process 121 without passing through process 120, and in process 121,
A fuel supply control signal Cf having a duty corresponding to the regular fuel supply iD set in process 113 is formed and supplied to the air-fuel ratio control valve 21, and then in process 1
Return to 02. As a result, if the engine is in a normal operating state after the fuel increase time Tf has elapsed from the start of fuel return, fuel is supplied to the engine at the regular fuel supply amount set in process 113.

While fuel supply control is being performed by the control unit lOO according to the program as described above, for example, as shown in FIGS. 5A and 5B, deceleration fuel cut is started at time tp, and the engine rotation is Assuming that the number N changes as shown in FIG. During the cut time Tc, the fuel supply to the engine is stopped, and from the fuel return start time tq until the fuel increase time Tf has elapsed, the engine is operated at the normal fuel supply fiD at the deceleration fuel cut time Tc and the time tp. Fuel is supplied to the engine in an amount in which a fuel increase amount ΔD (indicated by hatching in FIG. 5B) set according to the state is added, and after the fuel increase time Tf has elapsed, the regular fuel supply is resumed. Fuel will be supplied using iD.

In this way, immediately after the fuel is restored, an amount of fuel corresponding to the deceleration fuel cut time Tc and the operating state of the engine at the time of the deceleration fuel cut is added to the normal amount of fuel and supplied to the engine. The supply amount corresponds to the dry state of the inner wall surface of the intake passage 12, and therefore, the occurrence of torque shock, engine stop, etc. at the time of fuel recovery is suppressed without deteriorating fuel efficiency.

(Effects of the Invention) As is clear from the above description, in the engine fuel control device according to the present invention, when the operating state of the engine satisfies a predetermined condition, the fuel supply to the engine is stopped, and the engine When restarting the fuel supply to the engine, the system will supply the regular amount of fuel for a predetermined period of time from the point of restart, adding an amount of fuel depending on the operating state of the engine at the time the fuel supply was stopped. Immediately after, the amount of fuel supplied to the engine corresponds to the dryness of the inner wall of the intake passage, which makes it possible to suppress the occurrence of torque shock and engine stop when fuel is restored, and to effectively reduce fuel consumption. This means that it can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of an engine fuel control device according to the present invention in accordance with the claims, and FIG. 2 is a diagram showing an example of the engine fuel control device according to the present invention in an engine to which it is applied. 3 is a flowchart showing an example of a program executed by a microcomputer when a microcomputer is used in the control unit of the example shown in FIG. 2, and FIG. 4A, B , C and El, and FIGS. 5A and 5B are a characteristic diagram and a time chart, respectively, for explaining the operation of the example shown in FIG. In the figure, 10 is the engine body, 12 is an intake passage, 15 is a carburetor, 16 is a throttle valve, 22 is a negative pressure sensor, 32 is a rotation speed sensor, 34 is an idle switch, 36 is a neutral switch, 38 is a clutch switch, 41 is a water temperature sensor, 43 is an O2 sensor, 45 is an intake temperature sensor, 10
0 is a control unit. Figure 4 A B CD 1 Intake air temperature

Claims (1)

[Claims] an operating state detection means for detecting the operating state of the engine; a fuel supply means for supplying a regular amount of fuel to the engine according to the operating state based on a detection output obtained from the operating state detection means; When the operating state of the engine represented by the detection output obtained from the operating state detection means satisfies a predetermined condition, the supply means is caused to take a fuel supply stop state, and after the fuel supply stop state is taken, the above-mentioned Fuel for supplying an amount of fuel corresponding to the operating state of the engine in the fuel supply stop state in addition to the normal amount of fuel for a predetermined period of time from the time when the operating state of the engine no longer satisfies the predetermined condition. 1. A fuel control device for an engine, comprising a supply amount control means.